Glaucoma causes damage to optic nerve resulting into irreversible loss of vision. There are multiple factors involved but high intraocular pressure (IOP) plays an important role in the process of damage. High IOP is also a factor around which a whole range of treatment modalities revolve.
Glaucoma drainage devices of various types are the latest addition to the traditional treatment methods for glaucoma.
[Image by National Eye Institute/ CC BY 2.0]
Known as a “glaucoma drainage device,” “tube shunt,” “glaucoma valve,” or “Seton,” this procedure is often performed after other forms of glaucoma filtering surgery, most commonly trabeculectomy, have failed to adequately control intraocular pressure (IOP). Occasionally, it will be performed as an initial filtering procedure, usually in cases considered high risk for trabeculectomy failure, such as neovascular or inflammatory glaucomas. A drainage device consists of a small tube which is inserted into the eye, usually into the anterior chamber near the edge of the cornea, and a plastic plate which is placed outside the eye beneath the conjunctiva, the clear membrane which covers the eye. The plate serves a bit like a reservoir, creating a space for aqueous humor to collect, much like the bleb in trabeculectomy.